1. Field of Invention
This invention relates to a winder assembly comprising a spindle and a winder for rotating the spindle surrounded by a helical spring in order to wind the spring tightly around the spindle. Such an assembly may be suitably used for a music box containing an automatic instrument or the like.
2. Background Art
Known music boxes containing an automatic instrument and used as toys for little children are normally provided with a winder key having a threaded bore that forms a nut section. The winder key is removably fitted to the spindle of the music box through engagement of the threaded bore and a corresponding threaded section of the spindle or a bolt section, so that the winding of a helical spring arranged around the spindle may be tightened by hand to cause the automatic instrument of the music box to play music. However, if removed from the spindle, the winder key can become hazardous to small children because it is very small and can be easily swallowed by a little child. In an attempt to avoid this problem, a winder key which is nonremovably fitted to the spindle of a music box has been proposed in Japanese Utility Model No. Shou 58-193058.
However, the proposed winder key is accompanied by certain drawbacks. For one thing, it comprises a relatively large number of components and for another, it is so designed that it is prepared separately and independently from a matching automatic instrument and mounted to a product (such as a toy containing the automatic instrument) in the final stages of assembling operation by a toy maker. The toy maker is normally different from the manufacturer of the automatic instrument and the winder key, making mounting of the winder key cumbersome.
While the above described problem is resolved by the inventor of the present invention in a manner as disclosed in Japanese Utility Model No. Shou 62-163724, which teaches the use of a stopper having a claw for prevention of unintended removal of the winder key, this utility model is accompanied by a problem of elastic deformation of the arm of the stopper that can tilt and eventually release the winder key or a damaged claw of the stopper. Such a problem can occur particularly when the spindle and the winder key are disengaged but the claw is held in the groove of the spindle while the winder key is subjected to a lateral force.